The present invention relates to an openable side panel mechanism for selectively opening and closing a side panel on the bed or floor of a truck, a trailer, or other load carrying vehicles under the resilient forces applied by compression coil springs.
Attempts have heretofore been made to provide load carrying vehicles such as trucks and trailers, having a side cover or panel mounted on the horizontal floor and manually openable laterally of the vehicle for loading and unloading articles. The opening motion of the side panel is assisted by the biasing forces of springs coacting with a toggle mechanism as a relatively large force is required to open the side panel laterally. One such openable side panel device is disclosed by Japanese Utility Model Publication No. 54-2496. The disclosed arrangement includes a plurality of springs for biasing the side panel to be kept selectively in open and closed positions under the resilient forces of the springs which are reversible in direction while the side panel is being moved between the open and closed positions by a rope pulled by the operator. The springs employed are in the form of coil springs in order to keep the side panel urged in the closed position and to reduce the force required to open and close the side panel. The known side panel device is disadvantageous in that it is time-consuming and tedious to adjust the resilient forces of the springs individually to a suitable level. While the springs coact with the toggle mechanism to allow the side panel to be opened and closed with a smaller force and no braking force, the side panel is strongly biased in the open and closed positions and is relatively unstable at a midpoint or dead point between the open and closed positions. The side panel therefore has a tendency to shift toward either the open or the closed position at all times across the dead point, with the result that the side panel cannot be handled by the operator as desired. The side panel is supported on transverse beams mounted centrally on the truck bed at its front and rear ends, respectively. The transverse beams therefore should be heavy and rugged in construction. This requires that the side panel be fastened by the rope to avoid any danger of upward or downward displacement when the side panel is positioned somewhere between the open and closed positions.